Defining neurocognitive impairment in HIV: deficit scores versus clinical ratings

Abstract

Because HIV-related neurocognitive impairment is usually mild and variable, clinical ratings (CR) and global deficit scores (GDS) are recommended for detecting HIV-associated neurocognitive disorders (HAND). The CR approach requires impairment in at least two ability domains while the GDS considers number and severity of impairments across all measures. We examined classification agreement and clinical correlates of the two methods. Neurocognitive functioning of 1574 HIV-infected participants was assessed via a comprehensive, seven-domain neuropsychological battery. Global neurocognitive impairment was defined for each participant independently by CR and GDS. Participants were classified into four categories (Dually-normal, [impaired by] CR-only, [impaired by] GDS-only, or Dually-impaired). There was 83% concordance between CR and GDS classifications; in total, 56% of participants were deemed impaired by CR and 41% were classified as impaired by GDS. Impairment by GDS virtually guaranteed CR impairment, but 16% of participants were additionally classified as impaired only by CR. As compared to Dually-normal participants, those classified as Dually and CR-only impaired were more likely to have AIDS, have more severe co-occurring conditions, have more severe depressive symptoms, be unemployed, and have more everyday functioning complaints (ps < .05). Impairment classifications of the two methods were in high agreement; however, more people were classified as impaired using the CR approach compared to the GDS approach. Those impaired according to CR-only showed fewer neurocognitive and functional deficits than the Dually-impaired participants, but more of these deficits than Dually-normal participants. The CR approach may be most appropriate for detecting more subtle forms of neurocognitive impairment. Clinicians and researchers should recognize the strengths and weaknesses of each method when evaluating neurocognitive complications in HIV.

Figure 1

Frequency of classifications using the Clinical Ratings (CR) and Global Deficit Score (GDS) approaches. Proportion of agreement between the Clinical Ratings (CR) and Global Deficit Score (GDS); “Dually Normal” indicates those participants classified as cognitively normal by both methods; “Dually Impaired” indicates those participants classified as cognitively impaired by both methods. Dually Normal and Dually Impaired indicate the participants on which the CR and GDS agreed (83% of the sample). “Impaired by CR only” indicates those participants classified as cognitively impaired only by CR (and not GDS); “Impaired by GDS only” indicates those participants classified as cognitively impaired only by the GDS (and not CR).